Risk Factors (Genetics & Inherited Conditions)
The primary risk factor for Type I diabetes is having a parent or sibling with the disease. The most common type of diabetes, Type II, has multiple risk factors, both genetic and environmental. These include excessive food intake or unhealthy eating habits that result in obesity especially around the waist area, an inactive or sedentary lifestyle, increased age (over forty-five years old), high blood pressure (140/90 mmHg or greater), family history, gestational (during pregnancy) diabetes, and high cholesterol (HDL under thirty-five and triglycerides over 250 mg/dL). African Americans, Hispanic Americans, Pacific Islanders, and Native Americans have a higher incidence of diabetes.
(The entire section is 100 words.)
Etiology and Genetics (Genetics & Inherited Conditions)
Diabetes mellitus comprises a number of different diseases, primarily Type I and Type II diabetes. Genetics plays a role in both types of diabetes, although both are thought to result from the interaction between genetics and the environment. In both, the body’s ability to process sugars is impaired, with consequences that can lead to death if untreated. Glucose is a simple sugar required by all cells for normal functioning. Most of the body’s glucose initially comes from carbohydrates broken down during digestion. Normally, blood glucose rises when carbohydrates are ingested. At a certain level, the blood glucose triggers the pancreas to release insulin, causing the blood glucose level to drop by increasing the uptake in muscle, fat, the liver, and the gut.
Patients with either type of diabetes have difficulty metabolizing glucose, with a subsequent rise in fasting and postprandial (after meals) blood sugar levels. In Type I diabetes, also called juvenile-onset or insulin-dependent diabetes, this is caused by destruction of the insulin-secreting cells in the pancreas. In Type II (adult-onset, maturity-onset, or non-insulin-dependent diabetes), cells become resistant to the effects of insulin even though the pancreas is still producing some insulin.
Genetics plays a significant role in the development of diabetes. Type I diabetes mellitus is a chronic autoimmune disease that results from a combination of...
(The entire section is 893 words.)
Symptoms (Genetics & Inherited Conditions)
In Type I, the first recognizable symptom is a condition called prediabetes in which the usual insulin release in response to elevated blood sugar levels in the blood is diminished. At a certain point, commonly between the ages of ten and fourteen, the person develops full-blown diabetes, with excessive thirst and urination, as well as weight loss despite adequate or increased caloric intake. In Type II diabetes, symptoms may develop slowly over time and include excessive thirst and hunger, frequent urination, unexplained fatigue or weight loss, impaired healing of sores, higher incidence of infections, and blurred vision.
(The entire section is 97 words.)
Screening and Diagnosis (Genetics & Inherited Conditions)
Screening people at high risk but without symptoms can lead to early diagnosis and avert long-term chronic disease resulting from lack of therapeutic intervention. The American Diabetes Association recommends screening based on risks such as advanced age, family history, personal gestational history, and central obesity (apple-shaped body type with fat around the waist and upper body). The practice of screening is controversial but diabetes often goes undetected in the early stages and therefore untreated. Some research shows that screening is not cost-effective, while others state that this method of prevention can save the healthcare system the high cost of treatment for complications from untreated diabetes.
The methods of screening for diabetes generally begin with a random plasma glucose test. If this yields abnormal values, either the fasting plasma glucose test (FPG) or the fasting two-hour oral glucose tolerance test (GTT) is used. Values greater than 140 mg/dL for the FPG or greater than 200 mg/dL on the GTT require further assessment and intervention.
(The entire section is 163 words.)
Treatment and Therapy (Genetics & Inherited Conditions)
Treatment for Type I diabetes includes regular blood glucose monitoring and management with insulin. The person with Type I may need lifestyle changes to optimize self-care and minimize the possibility of other complications from the disease such as ketoacidosis. Choosing a healthy diet with regular meals, balanced with adequate activity and insulin, is essential for disease management. Consultation with a registered dietitian may be useful to choose meals and snacks with the proper amounts of carbohydrates and fats.
Type II diabetes treatment requires similar approaches, but the patient may try initial control with diet and exercise. If that approach is ineffective, therapy can progress to oral medications that increase tissue sensitivity to circulating insulin, stimulate increased insulin secretion, or alter insulin action. Later, insulin therapy may be necessary. Even with medication, successful therapy must include weight control through regular physical activity and diet modification.
Once the genetic factors related to diabetes have been completely elucidated for all types of diabetes, treatments to modify the genes may become a reality. Genome technology could remove the risks of side effects currently caused by treatment with medications.
(The entire section is 184 words.)
Prevention and Outcomes (Genetics & Inherited Conditions)
Although genetics has a definite role in the development of diabetes, personal choice can also impact the prevention of this disease. The primary prevention approaches for diabetes include choosing a healthy lifestyle and maintaining normal weight. Regular physical activity, balanced diet with adequate fiber and whole grains, weight loss to optimal level for the person’s height and build, not smoking, and early screening for those at high risk are important. The Centers for Disease Control and Prevention (CDC) recommends that people eat right and be active.
Both types of diabetes lead to increased risk of heart and vascular disease, kidney problems, blindness, neurological problems, and other serious medical consequences. Related health concerns include increased infections, delayed healing, foot and skin problems, depression, neuropathy (nerve damage), impaired vision, gingivitis, and dental disease.
(The entire section is 132 words.)
Further Reading (Genetics & Inherited Conditions)
Gibson, Greg. It Takes a Genome: How a Clash Between Our Genes and Modern Life Is Making Us Sick. Upper Saddle River, N.J.: Pearson Education, 2009. The author investigates the connection between human genes and the stressed culture that results in illness and disease.
Lowe, William L., Jr., ed. Genetics of Diabetes Mellitus. Boston: Kluwer Academic, 2001. An in-depth, scientifically based book written by multiple experts in the field of diabetes research.
McConkey, Edwin H. How the Human Genome Works. Sudbury, Mass.: Jones and Bartlett, 2004. Although the target audience are professionals in the health sciences, mature lay readers who want more information on the concept of the human genome can benefit from this book.
Milchovich, Sue K., and Barbara Dunn-Long. Diabetes Mellitus: A Practical Handbook. 8th ed. Boulder, Colo.: Bull, 2003. This basic reference book contains comprehensive information on living with diabetes.
Notkins, Abner Louis. “Immunologic and Genetic Factors in Type I Diabetes.” The Journal of Biological Chemistry 277, no. 46 (2002): 43, 545-543, 548. An overview of the major lines of evidence used to consider Type I diabetes primarily an autoimmune disease provides specifics about the gene defects involved in Type I diabetes.
Pavenec, Michal, et al. “Direct Linkage of Mitochondrial Genome Variation to Risk Factors for Type 2...
(The entire section is 300 words.)
Web Sites of Interest (Genetics & Inherited Conditions)
American Diabetes Association. http://www.diabetes.org
Diabetes Genome Anatomy Project. http://www.diabetesgenome.org/
Genetic Landscape of Diabetes. http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowTOC&rid=diabetes.TOC&depth=1
Human Genome Project Information. “Medicine and Genetics”. http://www.ornl.gov/sci/techresources/Human_Genome/medicine/medicine.shtml
National Human Genome Research Institute. http://www.genome.gov/
National Institute of Diabetes & Digestive & Kidney Diseases. http://www.niddk.nih.gov
Your Genes, Your Choice. http://www.ornl.gov/sci/techresources/Human_Genome/publicat/Genechoice/yourgenes.pdf
(The entire section is 95 words.)
Diabetes (Encyclopedia of Genetic Disorders)
Diabetes mellitus describes a group of diseases in which there is an elevated level of the sugar glucose, the body's main source of energy for cellular functions, in the blood. The level of glucose, as well as other "fuel" molecules, is increased due to a disorder in the production or function of the hormone insulin. A range of health problems occurs primarily due to the damaging effects of elevated levels of glucose on blood vessels.
To understand diabetes, it is important to understand how the hormone insulin functions in the breakdown and utilization of glucose. Insulin acts in two ways. It is necessary for the transport of glucose and other fuel molecules into the cells. It also regulates several pathways in metabolism that are important in the utilization of these fuel molecules. Insulin is made and released by specialized cells of the organ known as the pancreas. These beta cells of the pancreas release insulin when blood levels of glucose, amino acids, fatty acids, and ketones are high. These are all breakdown products of food, and an increase in their level in the blood signals that a person has recently eaten. The insulin acts to mobilize each of these fuel molecules so they can be used as energy to support cellular...
(The entire section is 4943 words.)